Real Images of what NASA found on freckled moon Europa
Jupiter's moon Europa is beautiful.
Have you ever seen it? Here it is.
This is not an artist concept, this isn't an illustration.
This amazing picture is showing the fascinating surface of Jupiter's icy moon
as seen by the Galileo orbiter, in the 1990s. This is the colour view of Europa that shows
the largest portion of the moon's surface at the highest resolution.
Colour variations across the surface are associated with
differences in geologic feature type and location.
For example, colours help us to distinguish areas containing water ice from the ones which include
non-ice components: we will talk about it later on in this video.
I would invite you to take a seat and a deep breath, cause
we're about to dive into this fantastic world. Are you ready? Let's go.
First, three young women who were captured by Jupiter for secret love shall be honoured,
[including] Europa, the daughter of Agenor... The second [moon] is called by me Europa...
Io, Europa, the boy Ganymede, and Callisto greatly pleased lustful Jupiter.
This was written by Simon Marius in 1614, in his famous Mundus Iovialis.
Simon Marius was a German astronomer, pupil of Tycho Brahe and Kepler.
In Mundu Iovialis he described the planet Jupiter and its moons. He was in dispute
with Galileo because he claimed to have discovered the four major moons a few days before Galileo.
Today we think that it's possible that Marius discovered the moons
of Jupiter independently of Galileo, but at least a few days after the Italian.
Whatever the exact order of the events, the mythological names of the four moons used today
(Io, Europa, Ganymede and Callisto) are those given to them by Marius.
Europa, in Greek Mythology, was the princess of Tire and queen of Creta.
(Europa Mythology:
The first time humanity observed Europa, was with Galileo.
In 1610, the famous scientist pointed his telescope towards Jupiter and discovered
the four Galilean satellites, which are known today as Io, Europa, Callisto and Ganymede.
It's hard to say which one of them is the most fascinating moon.
One could think about Io, the hellish world,o or to Ganymede, with its huge water ocean
underneath the frost. But Europa, this ball of silicate rock and water ice crust, is
amazing. Every time we look at it, we just Take a look at this picture.
It shows the four Galilean moons, from left to right, starting from Io and ending with Callisto.
New Horizons spacecraft had the honour to capture these pictures,
and NASA put them together in a single-family portrait of Jupiter's moons.
As you can clearly see, Europa is the smallest of them.
It is 3120 km in diameter, and New Horizon took this picture from a distance of about
3 million kilometres. If you look closely,
you can notice that Europa's surface is different from the surface of other moons.
It is an icy, smooth surface that likely conceals an ocean of liquid water.
Why is it so smooth? It seems craters are almost absent on Europa's surface.
Well, Europa is actually the smoothes known object in the Solar System. It lacks large
scale features such as mountains and craters. Considering that Europa is constantly hit by
cometary bombardment, we explain this smoothness by saying that the surface is really young,
with an estimated age which is about 20 to 180 million years old.
This finally means that surface is constantly and rapidly changing
However, does this mean that Europa's surface is boring?
Is it a surface without any features to note? Well, it ain't exactly so.
Scientists think for example that Europa's equator may be covered with ice in an unusual way.
Imagine polar regions on Earth: it has nothing to do with them.
According to one study, instead, icy spikes called penitentes are covering the moon Equator.
They could be up to 15 meters high, and vertical. Unluckily, we don't have pictures of these unusual
features, but radar and thermal data are consistent with this interpretation.
Also, as you can see from this picture taken by the Galileo orbiter spacecraft,
Europa has...freckles.
These reddish spots and shallows pits pepper the enigmatic ridged surface of Europa
Each of them is about 100 km across. The dark spots are called leniticulae,
the Latin term for freckles. Their similar sizes and spacing
suggest that Europa's ic shell may be churning away like a lava lamp, with warmer ice moving
upward from the bottom of the ice shell while colder ice near the surface skinks downward.
As we can read on the NASA website, surface features indicate that Europa could host life.
“Europa's surface has very few craters, indicating that recent or current geologic activity
has removed the traces of older impacts. The paucity of craters, coupled with other evidence,
has led scientists to surmise that there could be an ocean of liquid water beneath Europa's surface.
Where there is water, there could be life. This is why Europa is a target of current
interest for the study of the possibility of non-Earth life. A follow-up spacecraft
to Galileo will be Europa Orbiter, which should determine whether or not Europa has an ocean. “
Europa orbits Jupiter in three days and a half, at a distance from it of about 670.900 km.
Its orbit eccentricity is very small, with a value of only 0.009, which means that the orbit itself
is nearly circular. Europa is being pulled and stretched by Jupiter and other nearby moons.
As it comes slightly nearer to Jupiter, the gaseous planet
gravitational attraction increases, causing Europa to elongate toward and away from it.
As Europa moves slightly away from Jupiter, Jupiter's gravitational force decreases,
causing it to relax back into a more spherical shape. This creates tides in its ocean.
This tidal flexing gives Europa a source of heat, possibly allowing its ocean to stay liquid.
However, Europa's most striking surface features are a series of dark streaks
crisscrossing the entire globe, called lineae.
These lineae suggest that Europa's surface could host volcanoes.
This image, taken by the Galileo orbiter, shows features that may flow from ice volcanoes.
It was taken by the Galileo system during its seventh orbit around Jupiter.
The sun is illuminating the scene from the left. On the northwest corner of the image,
one can see features with shapes similar to lava flows on Earth.
The southern feature instead appears to have flowed over a ridge along its western edge.
This beautiful picture clearly shows the presence of lineae.
Colour variations across the surface are associated with differences in geologic feature
type and location. For example, areas that appear blue or white contain relatively pure water ice,
while reddish and brownish areas include non-ice components in higher concentrations.
The polar regions, visible at the left and right of this view,
are noticeably bluer than the more equatorial latitudes, which look more white. This colour
variation is thought to be due to differences in ice grain size in the two locations.
Okay, now we know a lot about the surface. What about the internal structure?
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As we've already said it is estimated that Europa is an outer layer of water around 100 km thick.
Underneath a crust of ice, there might be an ocean of liquid water.
Also, in order to understand what lies in the deepest layers,
astrophysicists studied Europa's magnetic field. Recent magnetic field data showed that Europa
has an induced magnetic field through interaction with Jupiter,
which suggests the presence of a subsurface conductive layer, thus reinforcing the
liquid water hypothesis. Europa is also likely to contain a metallic iron core.
One interesting thing about Europa is that you could... die if you were exposed to its radiation.
The radiation level at the surface of Europa is equivalent to a dose of about
5400 mSv (millisievert) per day,
an amount of radiation that would cause severe illness or death in human beings
exposed for a single Earth-day. The duration of a Europan day is approximately 3.5 times
that of a day on Earth, resulting in 3.5 times bigger radiation exposure.
Exploration of Europa began with the Jupiter flybys of Pioneer 10 and 11, in the seventies.
The first close-up photos were of very poor resolution compared to later missions.
Here's how Europa looked like to the eyes of Pioneer 10 spacecraft.
Then, in 1979, it was the time for the two Voyager probes.
They travelled through the Jovian System providing more detailed images of Europa's icy surface.
It was with the Voyager mission that scientists started to speculate about the possibility
of a liquid ocean underneath. Here are some pictures taken by the Voyager probes.
But this was not the end! In the 90s, NASA decided to
understand better Jupiter and its moons, as well as the asteroids Gaspra and Ide.
So they decided to launch a probe. The Galileo probe.
Galileo arrived on Jupiter in 1995, after gravitational assist flybys of Venus and Earth,
and became the first spacecraft to orbit Jupiter. Good job, Galileo!
The vast majority of the images we showed you so far
were in fact taken by the Galileo spacecraft. But I want to show you an incredible collage.
The mosaic on the right of the south polar region of Jupiter's moon Europa shows the
northern 290 kilometres of a strike-slip fault named Astypalaea Linea. The entire fault is about
810 kilometres long, the size of the California portion of the San Andreas fault on Earth
which runs from the California-Mexico border north to the San Francisco Bay.
The left mosaic shows the portion of the San Andreas fault near California's
San Francisco Bay that has been scaled to the same size and resolution as the Europa image.
Each covers an area of approximately 170 by 193 kilometres. The red line marks the once active
central crack of the Europan fault (right) and the line of the San Andreas fault (left).
They look very similar, don't they?
The only difference is the mechanisms that produced them.
As for Europa, fault motion is induced by tidal forces and
gravitational tug from Jupiter. Here on Earth, large strike-slip faults such as the San Andreas
are set in motion not by tidal pull, but by plate tectonic forces from the planet's mantle.
What about future missions on Europa? Conjectures regarding extraterrestrial
life have ensured a high profile for Europa and have led to steady lobbying for future missions,
so I think we will hear soon some news coming from this distant moon.
In particular, we will have Jupiter Icy Moon Explorer (JUICE),
which will include 2 flybys of Europa, even though it will be more focused on Ganymede.
Another important mission in the program is Europa Clipper.
Its aim is to explore Europa to investigate its habitability
and select sites for a future lander.
Imagine how amazing it would be to find that there's life on a moon in the solar system!
The only thing we can do is wait and, meanwhile, keep it curious.
"This video ends here! Thanks for watching everyone! Are you guys in love with Europa?
Let us know in the comments below! See you soon on the channel!